In order to stiffen of a high-rise building with a core structure, the location of the shear centre is crucial for the deformation analysis. Cross sections alternate from open to close through perforations in the core walls over the height of the core. So far, the Institute of Building Construction and Technology at the Vienna University of Technology has published three master theses about the course of shear centres in the core of high-rise buildings. The thesis of Zierhofer  dealt with physical measurement of several fixed test specimen different wall openings. Additional experiments were conducted in the thesis of Phüringer . He used the same specimen as , however, he analyzed them as single-span beam with clevis bearing. Both authors compared their physical measurements using a finite element analysis by RFEM, but in neither case did this lead to the desired result. Concluding from these theses, it was clear that further studies using additional finite element programs are necessary. Therefore, Thurner  performed a more precise numerical simulation with two additional finite element programs. This thesis aims to provide further insight into the behaviour of the shear centre course over height. For this, a numerical simulation of the different variants of the shear-flow-cleat, which is a device for applying a torsional moment in the form of a shear flow, is performed. Additionally, the influence of wall thickness on the shear centre position is analyzed where the thickness of the wall is varied in regard to the wall opening. Finally, the position of the wall openings is varied by providing perforations on two opposite walls. This work also gives a short overview of the horizontal loads, different stiffening systems and gives theoretical background to shear centres and torsion. Furthermore, elevator technology and simulations using the finite element programs RFEM and SOFiSTiK are addressed.